Placental abruption and risk for intraventricular hemorrhage in very low birth weight infants: the United States national inpatient database.

OBJECTIVE: To examine the association of placental abruption with intraventricular hemorrhage (IVH) in very low birth weight (VLBW) infants. METHODS: We examined the National Inpatient Sample (NIS) datasets. Preterm infants <1500 g birth weight (BW) were included. The odds ratios (OR) of developing IVH and severe IVH in association with placental abruption were calculated. Adjusted OR (aOR) were calculated using logistic regression models. RESULTS: The study included 113,445 VLBW infants. IVH occurred in 18.7% in the infants who were born to mothers with history of placental abruption versus 14.7% in infants without placental abruption, aOR 1.25 (95%CI: 1.13-1.38), p < 0.001. Severe IVH occurred in 6.4% in infants born to mothers with history of placental abruption versus 4.0% in those without placental abruption, aOR 1.53 (95%CI: 1.30-1.78), p < 0.001. CONCLUSION: Placental abruption is associated with increased prevalence of IVH and severe IVH in VLBW infants.

Differences in Electron and Hole Injection and Auger Recombination between Red, Green, and Blue CdSe-Based Quantum Dot Light Emitting Devices.

Despite the significant progress that has been made in recent years in improving the performance of quantum dot light-emitting devices (QLEDs), the effect of charge imbalance and excess carriers on excitons in red (R) vs green (G) vs blue (B) QLEDs has not been compared or systematically studied. In this work we study the effect of changing the electron (e)/hole (h) supply ratio in the QDs emissive layer (EML) in CdSe-based R-, G-, and B-QLEDs with inverted structure in order to identify the type of excess carriers and investigate their effect on the electroluminescence performance of QLEDs of each color. Results show that in R-QLEDs, the e/h ratio in the EML is >1, whereas in G- and B-QLEDs, the e/h ratio is <1 with charge balance conditions being significantly worse in the case of B-QLEDs. Transient photoluminescence (PL) and steady state PL measurements show that, compared to electrons, holes lead to a stronger Auger quenching effect. Transient electroluminescence (TrEL) results indicate that Auger quenching leads to a gradual decline in the EL performance of the QLEDs after a few microseconds, with a stronger effect observed for positive charging versus negative charging. The results provide insights into the differences in the efficiency behavior of R-, G-, and B-QLEDs and uncover the role of excess holes and poor charge balance in the lower efficiency and EL stability of B-QLEDs.

Changes in Hole and Electron Injection under Electrical Stress and the Rapid Electroluminescence Loss in Blue Quantum-Dot Light-Emitting Devices.

Blue quantum dot light-emitting devices (QLEDs) suffer from fast electroluminescence (EL) loss when under electrical bias. Here, it is identified that the fast EL loss in blue QLEDs is not due to a deterioration in the photoluminescence quantum yield of the quantum dots (QDs), contrary to what is commonly believed, but rather arises primarily from changes in charge injection overtime under the bias that leads to a deterioration in charge balance. Measurements on hole-only and electron-only devices show that hole injection into blue QDs increases over time whereas electron injection decreases. Results also show that the changes are associated with changes in hole and electron trap densities. The results are further verified using QLEDs with blue and red QDs combinations, capacitance versus voltage, and versus time characteristics of the blue QLEDs. The changes in charge injection are also observed to be partially reversible, and therefore using pulsed current instead of constant current bias for driving the blue QLEDs leads to an almost 2.5× longer lifetime at the same initial luminance. This work systematically investigates the origin of blue QLEDs EL loss and provides insights for designing improved blue QDs paving the way for QLEDs technology commercialization.

Lifetime enhancement in QDLEDs via an electron-blocking hole transport layer.

This study investigates the impact of an engineered hole transport layer (HTL) on the stability of electroluminescent quantum dot light-emitting devices (QDLEDs). The 9-Phenyl-3,6-bis(9-phenyl-9Hcarbazol-3-yl)-9H-carbazole (Tris-PCz) HTL, which possesses a shallower lowest unoccupied molecular orbital (LUMO) energy level compared to the widely used 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP) HTL, is employed to confine electron overflow toward the HTL. Utilizing the Tris-PCz HTL results in a 20× improvement in the electroluminescence half-life (LT50) of QDLEDs compared with conventional QDLEDs using the CBP HTL. Electric and optoelectronic analyses reveal that the migration of excess electrons toward the HTL is impeded by the up-shifted LUMO level of Tris-PCz, contributing to prolonged operational device stability. Furthermore, the augmented electric field at the QD/Tris-PCz interface, due to accumulated electrons, expedites hole injection rates, leading to better charge injection balance and the confinement of the exciton recombination zone within the QD and thus the device stability enhancement. This study highlights the significant influence of the HTL on QDLED stability and represents one of the longest LT50 for a QDLED based on the conventional core/shell QD structure.

Influence of Encapsulation on the Efficiency and Positive Aging Behavior in Blue Quantum Dot Light-Emitting Devices.

Encapsulating blue quantum dot light-emitting devices (QLEDs) using an ultraviolet curable resin is known to lead to a significant increase in their efficiency. Some of this efficiency increase occurs immediately, whereas some of it proceeds over a period of time, typically over several tens of hours following the encapsulation, a behavior commonly referred to as positive aging. The root causes of this positive aging, especially in blue QLEDs, remain not well understood. Here, it is revealed that contrary to the expectation, the significant improvement in device efficiency during positive aging arises primarily from an improvement in electron injection across the QD/ZnMgO interface and not due to the inhibition of interface exciton quenching as is widely believed. The underlying changes are investigated by XPS measurements. Results show that the enhancement in device performance arises primarily from the reduction in O-related defects in both the QDs and ZnMgO at the QD/ZnMgO interface. After 51.5 h, the blue QLEDs reach the optimal performance, exhibiting an EQEmax of 12.58%, which is more than sevenfold higher than that in the control device without encapsulation. This work provides design principles for realizing high efficiency in blue QLEDs with oxide electron-transporting layers (ETLs) and provides a new understanding of the mechanisms underlying positive aging in these devices and thus offers a new starting point for both fundamental investigations and practical applications.

Inverted Solution-Processed Quantum Dot Light-Emitting Devices with Wide Band Gap Quantum Dot Interlayers.

Despite its benefits for facilitating device fabrication, utilization of a polymeric hole transport layer (HTL) in inverted quantum dots (QDs) light-emitting devices (IQLEDs) often leads to poor device performance. In this work, we find that the poor performance arises primarily from electron leakage, inefficient charge injection, and significant exciton quenching at the HTL interface in the inverted architecture and not due to solvent damage effects as is widely believed. We also find that using a layer of wider band gap QDs as an interlayer (IL) in between the HTL and the main QDs' emission material layer (EML) can facilitate hole injection, suppress electron leakage, and reduce exciton quenching, effectively mitigating the poor interface effects and resulting in high electroluminescence performance. Using an IL in IQLEDs with a solution-processed poly(9,9-dioctylfluorene-alt-N-(4-sec-butylphenyl)-diphenylamine) (TFB), HTL improves the efficiency by 2.85× (from 3 to 8.56%) and prolongs the lifetime by 9.4× (from 1266 to 11,950 h at 100 cd/m2), which, to the best of our knowledge, is the longest lifetime for an R-IQLED with a solution-coated HTL. Measurements on single-carrier devices reveal that while electron injection becomes easier as the band gap of the QDs decreases, hole injection surprisingly becomes more difficult, indicating that EMLs of QLEDs are more electron-rich in the case of red devices and more hole-rich in the case of blue devices. Ultraviolet photoelectron spectroscopy measurements verify that blue QDs have a shallower valence band energy than their red counterparts, corroborating these conclusions. The findings in this work, therefore, provide not only a simple approach for achieving high performance in IQLEDs with solution-coated HTLs but also novel insights into charge injection and its dependence on QDs' band gap as well as into different HTL interface properties of the inverted versus upright architecture.

Significant Lifetime Enhancement in QLEDs by Reducing Interfacial Charge Accumulation via Fluorine Incorporation in the ZnO Electron Transport Layer.

ZnO nanoparticles are widely used for the electron transport layers (ETLs) of quantum dots light emitting devices (QLEDs). In this work we show that incorporating fluorine (F) into the ZnO ETL results in significant enhancement in device electroluminescence stability, leading to LT50 at 100 cd m-2 of 2,370,000 h in red QLED, 47X longer than the control devices. X-ray photo-electron spectroscopy, time-of-flight secondary ion mass spectroscopy, photoluminescence and electrical measurements show that the F passivates oxygen vacancies and reduces electron traps in ZnO. Transient photoluminescence versus bias measurements and capacitance-voltage-luminance measurements reveal that the CF4 plasma-treated ETLs lead to increased electron concentration in the QD and the QD/hole transport layer interface, subsequently decreasing hole accumulation, and hence the higher stability. The findings provide new insights into the critical roles that optimizing charge distribution across the layers play in influencing stability and present a novel and simple approach for extending QLED lifetimes.

The Root Causes of the Limited Electroluminescence Stability of Solution-Coated Versus Vacuum-Deposited Small-Molecule OLEDs: A Mini-Review.

Using solution-coating methods for the fabrication of organic light-emitting devices (OLEDs) offers a tremendous opportunity for enabling low-cost products and new applications. The electroluminescence (EL) stability of solution-coated (SOL) OLEDs, however, is significantly lower than that of vacuum-deposited (VAC) OLEDs, causing their operational lifetimes to be much shorter-an issue that continues to hamper their commercialization. The root causes of the lower EL stability of these devices remain unclear. This article briefly reviews and summarizes some of the work that has been done to-date for elucidating the root cause of the lower EL stability of SOL OLEDs, giving special attention to studies where side-by-side comparisons of SOL and VAC devices of the same materials have been conducted. Such comparisons allow for more-reliable conclusions about the specific effects of the solution-coating process on device stability to be made. The mini-review is intended to introduce the work done to-date on the causes of lower stability in SOL OLEDs and to stimulate further work for the purpose of closing the existing knowledge gap in this area and surmounting this long-standing challenge in the SOL OLED technology.

Role of Guest Materials in the Lower Stability of Solution-Coated versus Vacuum-Deposited Phosphorescent OLEDs.

Utilizing different phosphorescent materials as emitter guests, this work investigates the root causes of the lower electroluminescence (EL) stability of solution-coated (SOL) organic light-emitting devices (OLEDs) relative to their vacuum-deposited (VAC) counterparts. The results show that emitter guest molecules aggregate under electrical stress, leading to the emergence of new longer-wavelength bands in the EL spectra of the devices over time. However, the intensity of these aggregation emission bands is much stronger in the case of SOL host:guest systems than that of their VAC counterparts, indicating that guest aggregation occurs much faster in the former. The results reveal that the phenomenon arises from differences in the initial morphologies and are likely associated with the use of solvents in the solution-coating process. Moreover, although excitons can drive this aggregation in the case of SOL emissive layer (EML) devices, the coexistence of excitons and polarons accelerates this phenomenon significantly. The results uncover one of the main causes of the lower stability of OLEDs made by solution coating and reveal the importance of adopting new molecular designs that make them less susceptible to aggregation for the development of SOL OLEDs with high performance.

Prognostic Impact of BRCA1 and BRCA2 Mutations on Long-Term Survival Outcomes in Egyptian Female Breast Cancer Patients.

Evidence on the prognostic relevance of BRCA1/2 mutations on breast cancer survival is still debatable. To address this ambiguity, we sought to elucidate the impact of BRCA1/2 mutation carriership on long-term clinical outcomes for the first time in Egyptian female breast cancer patients. This study comprised 103 Egyptian female breast cancer patients previously tested for BRCA1/2 mutations. Clinicopathological characteristics and long-term follow-up data were retrieved from clinical records until death or loss to follow-up. Overall survival (OS), recurrence-free survival (RFS), disease-free survival (DFS), and metastasis-free survival (MFS) were compared in BRCA1/2 mutation carriers and non-carriers. Pathogenic variants (Class 5 according to ACMG/AMP guidelines) were observed in 29 cases. The profile of the detected variants was previously reported. After median follow-up time of 6.9 years (range, 4.2-24.4 years), BRCA1/2 carriers exhibited significantly worse RFS compared to non-carriers (p = 0.01; HR = 3.00 (95%CI 1.35-6.68)). However, we couldn't demonstrate statistically significant difference between carriers of pathogenic mutations and non-carriers regarding MFS (p = 0.24; HR = 1.38 (95%CI 0.8-2.4)), DFS (p = 0.11; HR = 1.23 (95%CI 0.74-2.06)), or OS (p = 0.36; HR = 1.23 (95%CI 0.58-2.61)). Though no significant impact was observed in OS, yet BRCA1/2 mutation carriers were at high risk of recurrence, highlighting the importance of adopting BRCA screening strategies and prophylactic measures.

Breast-Gynaecological & Immuno-Oncology International Cancer Conference (BGICC) Consensus and Recommendations for the Management of Triple-Negative Breast Cancer.

Background: The management of patients with triple-negative breast cancer (TNBC) is challenging with several controversies and unmet needs. During the 12th Breast-Gynaecological & Immuno-oncology International Cancer Conference (BGICC) Egypt, 2020, a panel of 35 breast cancer experts from 13 countries voted on consensus guidelines for the clinical management of TNBC. The consensus was subsequently updated based on the most recent data evolved lately. Methods: A consensus conference approach adapted from the American Society of Clinical Oncology (ASCO) was utilized. The panellists voted anonymously on each question, and a consensus was achieved when ≥75% of voters selected an answer. The final consensus was later circulated to the panellists for critical revision of important intellectual content. Results and conclusion: These recommendations represent the available clinical evidence and expert opinion when evidence is scarce. The percentage of the consensus votes, levels of evidence and grades of recommendation are presented for each statement. The consensus covered all the aspects of TNBC management starting from defining TNBC to the management of metastatic disease and highlighted the rapidly evolving landscape in this field. Consensus was reached in 70% of the statements (35/50). In addition, areas of warranted research were identified to guide future prospective clinical trials.

Significant enhancement in quantum-dot light emitting device stability via a ZnO:polyethylenimine mixture in the electron transport layer.

The effect of adding polyethylenimine (PEI) into the ZnO electron transport layer (ETL) of inverted quantum dot (QD) light emitting devices (QDLEDs) to form a blended ZnO:PEI ETL instead of using it in a separate layer in a bilayer ZnO/PEI ETL is investigated. Results show that while both ZnO/PEI bilayer ETL and ZnO:PEI blended ETL can improve device efficiency by more than 50% compared to QDLEDs with only ZnO, the ZnO:PEI ETL significantly improves device stability, leading to more than 10 times longer device lifetime. Investigations using devices with marking luminescent layers, electron-only devices and delayed electroluminescence measurements show that the ZnO:PEI ETL leads to a deeper penetration of electrons into the hole transport layer (HTL) of the QDLEDs. The results suggest that the stability enhancement may be due to a consequent reduction in hole accumulation at the QD/HTL interface. The findings show that ZnO:PEI ETLs can be used for enhancing both the efficiency and stability of QDLEDs. They also provide new insights into the importance of managing charge distribution in the charge transport layers for realizing high stability QDLEDs and new approaches to achieve that.

Significant Enhancement in Quantum Dot Light-Emitting Device Stability via a Cascading Hole Transport Layer.

This work investigates the effect of the hole transport layer (HTL) on the stability of electroluminescent quantum dot light-emitting devices (QDLEDs). The electroluminescence half-life (LT50) of QDLEDs can be improved by 25× through the utilization of a cascading HTL (CHTL) structure with consecutive steps in the highest occupied molecular orbital energy level. Using this approach, a LT50 of 864,000 h (for an initial luminance of 100 cd m-2) is obtained for red QDLEDs using a conventional core/shell QD emitter. The CHTL primarily improves QDLED stability by shifting excessive hole accumulation away from the QD/HTL interface and toward the interlayer HTL/HTL interfaces. The wider electron-hole recombination zone in the CHTL for electrons that have leaked from the QD layer results in less HTL degradation at the QD/HTL interface. This work highlights the significant influence of the HTL on QDLED stability and represents the longest LT50 for a QDLED based on the conventional core/shell QD structure.

Telemedicine, a tool for follow-up of infants discharged from the NICU? Experience from a pilot project.

OBJECTIVE: Follow-up of infants from the NICU by neonatologist is limited to premature and complicated infants although parents of infants with advanced gestation may have concerns as well. We compared parental questions of infants < 35 weeks gestation (group A), during virtual telemedicine visits, to ≥35 week infants (group B). STUDY DESIGN: In a retrospective cohort study, questions asked by parents were extracted from the electronic medical record of all infants post discharge from the NICU, after their pediatrician visit. RESULTS: Gestation and birth weight of infants in group A were significantly lower than group B but their stay was longer. There were no significant differences in the number of parents who had questions, between the groups (A 68.1% vs B 67.3%, p = 0.91, 95% CI 0.46-1.99, OR = 0.96). CONCLUSIONS: Telemedicine is a feasible tool for follow-up of NICU infants post discharge. Parents of infants with advanced gestation and weight may benefit from NICU follow-up.

The role of excitons within the hole transporting layer in quantum dot light emitting device degradation.

This work investigates the root causes of the limited stability of electroluminescent quantum dot light-emitting devices (QDLEDs). Studies using electrical measurements, continuous UV irradiation, and both steady-state and transient photoluminescence (PL) spectroscopy reveal that exciton-induced degradation of the hole transporting material (HTM) in QDLEDs plays a role in limiting their electroluminescence (EL) stability. The results indicate that there is a correlation between device EL stability and the susceptibility of the HTM to exciton-induced degradation. The presence of quenchers in the HTM layer can lead to a decrease in the luminescence quantum yield of QDs, suggesting that energy transfer between the QD and HTM films may play a role in this behavior. The results uncover a new degradation mechanism where excitons within the HTM limit the EL stability of QDLEDs.

Root Causes of the Limited Electroluminescence Stability of Organic Light-Emitting Devices Made by Solution-Coating.

Although organic electroluminescent materials have long promised the prospect of making organic light emitting devices (OLEDs) via low-cost solution-coating techniques, the electroluminescence stability of devices made by such techniques continues to be rather limited making them unsuitable for commercialization. The root causes of the lower stability of OLEDs made by solution-coating versus the more conventional vacuum-deposition remain unknown. In this work, we investigate and compare between solution-coated and vacuum-deposited materials under prolonged excitation, using the archetypical host material 4,4'-bis( N-carbazolyl)-1,1'-biphenyl as a model OLED material. Results show that solution-coated films are more susceptible to degradation by excitons in comparison to their vacuum-deposited counterparts, resulting in a faster decrease in their luminescent quantum yield. The degradation rate also depends on the choice of solvent that was used in the solution-coating process. Results also show that the decrease in quantum yield is caused by exciton-induced chemical decomposition in the material as well as some possible molecular reorganization or aggregation, both of which are induced by excitons and proceed more quickly in case of solution-coated films. The faster degradation in the solution-coated films appears to originate primarily from their different morphological makeup and not due to chemical impurities. The findings uncover what appears to be one of the fundamental root causes of the lower stability of solution-coated OLEDs in general.

Electroplex as a New Concept of Universal Host for Improved Efficiency and Lifetime in Red, Yellow, Green, and Blue Phosphorescent Organic Light-Emitting Diodes.

A new concept of host, electroplex host, is developed for high efficiency and long lifetime phosphorescent organic light-emitting diodes by mixing two host materials generating an electroplex under an electric field. A carbazole-type host and a triazine-type host are selected as the host materials to form the electroplex host. The electroplex host is found to induce light emission through an energy transfer process rather than charge trapping, and universally improves the lifetime of red, yellow, green, and blue phosphorescent organic light-emitting diodes by more than four times. Furthermore, the electroplex host shows much longer lifetime than a common exciplex host. This is the first demonstration of using the electroplex as the host of high efficiency and long lifetime phosphorescent organic light-emitting diodes.

Multifunctional Dithiadiazolyl Radicals: Fluorescence, Electroluminescence, and Photoconducting Behavior in Pyren-1'-yl-dithiadiazolyl.

The pyren-1'-yl-functionalized dithiadiazolyl (DTDA) radical, C16H9CNSSN (1), is monomeric in solution and exhibits fluorescence in the deep-blue region of the visible spectrum (440 nm) upon excitation at 241 nm. The salt [1][GaCl4] exhibits similar emission, reflecting the largely spectator nature of the radical in the fluorescence process, although the presence of the radical leads to a modest quenching of emission (ΦF = 98% for 1+ and 50% for 1) through enhancement of non-radiative decay processes. Time-dependent density functional theory studies on 1 coupled with the similar emission profiles of both 1+ and 1 are consistent with the initial excitation being of predominantly pyrene π-π* character. Spectroscopic studies indicate stabilization of the excited state in polar media, with the fluorescence lifetime for 1 (τ = 5 ns) indicative of a short-lived excited state. Comparative studies between the energies of the frontier orbitals of pyren-1'-yl nitronyl nitroxide (2, which is not fluorescent) and 1 reveal that the energy mismatch and poor spatial overlap between the DTDA radical SOMO and the pyrene π manifold in 1 efficiently inhibit the non-radiative electron-electron exchange relaxation pathway previously described for 2. Solid-state films of both 1 and [1][GaCl4] exhibit broad emission bands at 509 and 545 nm, respectively. Incorporation of 1 within a host matrix for OLED fabrication revealed electroluminescence, with CIE coordinates of (0.205, 0.280) corresponding to a sky-blue emission. The brightness of the device reached 1934 cd/m2 at an applied voltage of 16 V. The crystal structure of 1 reveals a distorted π-stacked motif with almost regular distances between the pyrene rings but alternating long-short contacts between DTDA radicals. Solid state measurements on a thin film of 1 reveal emission occurs at shorter wavelengths (375 nm) whereas conductivity measurements on a single crystal of 1 show a photoconducting response at longer wavelength excitation (455 nm).

The role of polyethylenimine in enhancing the efficiency of quantum dot light-emitting devices.

Although the use of polyethylenimine (PEI) in quantum dot light-emitting devices (QDLEDs) has recently been found to improve efficiency, the mechanism behind this increase has been disputed in the literature. In this work, we conduct investigations to elucidate the role of PEI in enhancing QDLED efficiency. Spectroscopic studies of devices with a phosphorescent marking layer reveal that the PEI layer increases, rather than decreases, the generation of excitons within the hole transporting layer indicative of increased electron injection. Delayed electroluminescence measurements corroborate these findings as devices with a PEI interlayer exhibit a greater concentration of excess mobile and trapped electrons. We attribute the improvement in efficiency despite the ensuing increased charge imbalance within the devices to the passivation of exciton quenching at the ZnO/QD interface. The increase in efficiency predominantly occurs over low driving currents which is particularly attractive for the brightness targets of display applications. Furthermore, despite the increased charge imbalance, the PEI passivation layer appears to have little effect on QDLED stability. This shows that excess electrons and Auger quenching by unneutralized electrons are not detrimental to QDLED stability.

Electroluminescence Stability of Organic Light-Emitting Devices Utilizing a Nondoped Pt-Based Emission Layer.

We study the effects of using an emitting material (Pt(II) bis(3-(trifluoromethyl)-5-(2-pyridyl)pyrazolate-Pt(fppz)2) characterized by a preferred horizontal dipole alignment and a nearly unitary quantum yield regardless of concentration on the lifetime of organic light-emitting devices (OLEDs). Using such a material as a dopant in increasingly higher concentrations is found to lead to an increase in device stability, a trend that is different from that commonly observed with conventional OLED guests. The results are consistent with the newly discovered exciton-polaron-induced aggregation degradation mechanism of OLED materials. When this emitter is used as a neat emission layer, the material is already in a highly aggregated state, and the device is no longer affected by exciton-polaron interactions. The results demonstrate the potential stability benefits of using such materials in OLEDs.